Dental impression tray



Aug. 3, 1954 w. H. THOMPSON 2,685,134

DENTAL IMPRESSION TRAY Filed Jan. 26, 1952 IN V EN T 0R. %///km 74am :on.

Patented Aug. 3, 1954 UNITED STATES PATENT OFFICE DENTAL MPRESSION TRAY William Houston Thompson, Pittsburgh, Pa. Application January 26, 1952, Serial No. 268,384

2 Claims.

This invention relates to dental impression trays. More particularly, the invention relates to an impression tray that is sanitary and will become so firmly connected with the impression material therein that the gum impression will not be disturbed in removing the tray from the mouth, said tray bein inexpensive, so that it will be discarded after once being used.

The commonly used dental impression tray is made of thin metal with a metal handle attached to the bottom thereof. Most trays have openings by which to anchor the impression material in the tray. After the tray has been used to make a gum impression, the impression material is dug out of the tray so that it may be used again. The impression material adheres to the tray and gets very hard, so that it is diflicult to clean the tray and make it sanitary. Since such metal trays are not destroyed when used, it is common practice to clean and re-use them.

The primary object of the present invention is to provide a dental impression tray that is effective for obtaining gum and tooth impressions, and is sufficiently inexpensive so that it may be discarded after use for making an impression.

Another object of the invention is to provide a dental tray which will firmly anchor the impression material therein, but will effectively seal the sensitive tissues of the mouth from contact with the impression material.

A further object of the invention is to provide an impression tray that may be made of a moisture-proof plastic material that is strong and sanitary.

With these and other objects in view, the invention consists in the improved dental impression tray as hereinafter illustrated and described and defined in the appended claims.

The various features of the inventionare illustrated in the accompanying drawings, in which:

Fig. 1 is a top perspective view of an impression tray, for the lower jaw, embodying the preferred form of the invention;

Fig. 2 is a bottom perspective view of the tray shown in Fig. 1; and

Fig. 3 is a bottom perspective view of a tray for making the impression of the upper jaw.

Referring to the drawings, the tray for making the impression of the gums and teeth of the lower jaw is shown in Figs. 1 and 2. The tray 8 is made up of a thin water-proof material which may be metal or of a composition or plastic material. The tray consists of a U-shaped channel I which is provided with perforations [2 throughout the face of the channel. When impression material is placed within the channel for the purpose of making the lower jaw impression, the impression material will pass through the perforations to be firmly anchored in the channel when the impression material hardens. The inside of the channel forms an opening M to provide a space for the tongue, and a flange I6 integral with the top of the inside wall of the channel is positioned close to and covers the wall to prevent impression material which extends through the open ings in the side of the channel from coming into contact with the sensitive tissues of the tongue. The smooth top of the outside edge is of the channel is the impression periphery which is formed in the mouth, and this periphery forms a tight connection with walls of the mouth to firmly hold the tray in the mouth after the impression has been made and the material has set. From the peripheral edge [8 a protecting flange 20 extends dolwnwardly around the outside of the outside wall of the channel to prevent impression material which extends through the openings in the channel outside wall from coming into contact with the tissues of the mouth. A handle 22 is formed as an integral part of the flange 20 so that the handle itself extends from the peripheral impression edge l8 down even with the bottom of the flange. Reinforcing ribs 24 are formed at each side of the handle from the tray material which makes a strong handle and permits the necessary pressure to be applied by the handle to release the tray from the mouth after the impression has been made. Since the greatest pressure is required to release or break the vacuum under the tray at the impression periphery, it is important that the pressure exerted through the handle 22 shall be concentrated around the peripheral impression edge.

As illustrated in Fig. 2, a central rib 26 and side ribs 28 are formed on the bottom of the channel, the ribs 28 being opposite the bottom of the channel, and the rib 26 bein in the center of the front end of the channel. These ribs act to strengthen the thin material from which the tray is made, in order to make it strong enough to withstand the pressure which is required in releasing the tray from the mouth.

In Fig. 3 is illustrated the form of tray 30 used in making the impression of the gums and teeth of the upper jaw. This tray differs from the tray 8 shown in Figs. 1 and 2 in that the central tongue opening I 4 is not required, and according- 1y a web 32 extends across the bottom of the tray from one leg of the U-shaped channe1 to the proof rlber plastic material, or metal. .trays-may-be made by the-use of dies so asg to be other leg. Reinforcing ribs 34 are formed on the bottom of the tray opposite the position of the U-shaped channel of the tray 30. A central V- shaped rib 36 is formed on the back of the tray 30, which connects with the front ends of the ribs 34. The U-shaped channel in the tray 30 is similar in shape to the U-shaped channel 10, but is usually broader on account of the shape of the upper jaw. The outside protecting flange 2B of the trayl3ll is similar in construction to the flange 20 on the ---tray H). The handle 22 for the tray 30 is the same in construction as that illustrated and described with reference to the tray shown in Figs. 1 and 2.

The flanges I6 and 20 have been found to play a very important part in obtaining agoodi-mpression of the gums and teeth. -.The impression plastic which is used in the tray channel is quite fluid and will readily flow through the holes 12 when the tray is placed in a mouth to obtain an impression. The space between the outside of the-ehannel andthe inside of the flange-will soon 'fill-g-withplastic and; after the space is filled, the flange preventfurther-rem vaI of the impression plastic from thechannel. sothat plenty of plastic will be available to make an impression.

-A dentist in makingan impression-exerts considerable; pressure in forcing the impression tray against the jaws. -With. the tray of the present .invention, the-flangespermit the obtaining of a good impression which'accurately conforms to the shape of the jawbones and the muscles in the mouth. The flanges are flexible and-when the space between the flangesand the tray channel -is filled with'impression plastic, theflange will 1 move under the-pressure appliedto the trayto force plastic into thechannel or receive additional plastic from the'channel asthe flanges movein accordance withthe shapeof the oral cavity to obtain an impression'for'any' of the various shapes of; jaw bones and mouth muscles.

It has been found in practice that it is-necessary to maintain a stock of four to-v six sizes of each ofthetrays; 8and.3fl in order to provide for-making impressions of mouths of differentsizes. A

caliper has been-developed-by which the shape rand size of the jaw may 7 be a measured in. order to. indicatewhat size of trayis to-be used.

The traymay-be made of any desiredmoisture- These molded. or pressed into. shape. Plastic rnaterial iswell adapted for. this purpose, in that the plastic may be inserted into the dies and heat molded .so that the plastic will be fluidwhen being formed.

The shape of. the tray will dependentirelyupon the shape-ofthe die s, and it isydesirablethat-the impression periphery 18 or the ,topof. the channel wall to the bottom thereof and spaced from the .wallr; to fo rm a chamber between the outside wall and the flangea series of perforations in the outside wall, said solid flange being shaped to contact the. tissues of the-mouth and prevent impression material from coming into contact with mouth tissues, a handle extending across a major portion of the front of the traybeing an integral part of thefront portionof the solid flange'and united to the top of the outside channel wall, said handle having a reinforcing rib formed at each side thereof which extends from the top of the channel wall tothe bottom level of the solid flange.

2. A dental tray comprising a waterproof fiber reinforced plastic material formed into a tray having a U-shaped channel open at thetop and at; the terminals of the U, a solid flange integral withthe top of the wall at the outside of the channel and extending down across the outside wall to the bottom thereof, said flange being spaced from the wall to form a chamber there "between, a series of perforationsin the outside shaped channel and a solid tissue protecting flange integral with the channel extends from the top of 'the inside channel wall down around the -insi:de;wa1l .to the full height of the channel to .prevent impression material from coming into -.contact with-the tissue of the tongue.

References Cited inthe file of this patent .UNITED STATES PATENTS 

